In a square baler, crop is picked up from the ground by means of a rotary pickup having radially projecting tines. The crop picked up from the ground is advanced towards a rotor arranged at the lower end of an arcuate chute. The rotor serves to compress the crop into the arcuate chute, the latter acting as a pre-compression chamber.
When a plunger reciprocating in a baling chamber of the baler is at the bottom dead centre position of its reciprocating cycle, a stuffer displaces the crop present in the pre-compression chamber into the baling chamber, the crop becoming a slice of the bale in the process of being formed. Once the bale in the baling chamber has reached a certain size, twine is wrapped around the bale and knotted to form a finished bale. The finished bale remains in the baling chamber while the next bale is being formed and is eventually discharged from the rear end of the baler.
As square balers are well known and documented, it is believed that the above brief description will suffice for an understanding of the present invention.
In order to produce well formed bales of uniform density, it is desirable to ensure that the density of the crop in the pre-compression chamber is at a desired level when a stuffer cycle is initiated. The stuffer cycle must of course be synchronised with the movement of the plunger of the baling chamber and can only take place at the end of a whole number of cycles of the plunger in the baling chamber.
If, for example, a stuffer cycle is performed every three cycles of the plunger in the baling chamber, it would be undesirable for the crop density in the pre-compression chamber to reach the desired level either after two and half plunger cycles or three and half plunger cycles. In the former case, the crop density would be too great by the time the crop is transferred to the baling chamber. In the latter case, if a stuffer cycle is initiated by a pressure sensor in the pre-compression chamber, the stuffer cycle could be delayed by a complete plunger cycle.